The message "non-system disk or disk error" can be one of the more confusing messages to receive on your desktop or laptop computer, particularly if you haven't seen it before. In some cases it can be easily solved by removing a disk from a drive, but in other cases it can be a sign of a more serious hardware problem or a significant loss of data.
Non-System Disk or Disk Error
The message "non-system disk or disk error" actually means that a computer has detected one of two problems. If you see it, you'll normally see it when a computer is starting up or rebooting.
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One is that a non-system disk, meaning one that doesn't contain information needed to load an operating system, is in a drive where the computer is looking for instructions on how to start up. The non-system disk error originates because the computer is unable to proceed without an operating system to load.
If you see this error and there's a disk in a CD drive or even a floppy drive on the computer, try removing the disk. Press a key to continue if prompted to do so or, if need be, restart the machine and see if the error goes away.
If you think the disk is a system disk that can be used to boot the computer, try reading it once the computer loads normally to see if it contains what you think it does and isn't damaged. If you have another computer handy, see if it can be used to read the disk or if the disk will start that computer. If it works normally in another computer, there may be a problem with your computer's disk drive that's keeping it from reading the disk.
If There's No Disk
If there's no disk in the drive and you receive the message, there's generally either a problem with the drive that makes the computer falsely believe it contains a disk or, more commonly, there's a problem with the hard drive.
If you just got the computer or just installed the hard drive, it's possible that it's working correctly but doesn't have an operating system on it. In that case, you'll need to do one of three things: find a bootable disk or USB drive, like a DVD or CD, that you can use to start the computer and install an operating system on the hard drive; put the drive into another computer to load a system on it; or simply replace the drive.
Bootable disks often come with computers for use in restoring your system if you have a problem, and you can download burnable disk images from operating system vendors including Microsoft, Apple and many Linux distributors.
If the computer has previously been working and there's no disk in a drive, the error may be a sign of a hard-drive problem or damage to the data on the drive. You may hear unusual noises if the hard drive is physically damaged. You can connect the drive to another computer to see if it is working and has data on it. If you're not sure how to do this, contact a technician for help or invoke your computer's warranty or service plan if it's covered.